Sand blast apparatus

ABSTRACT

A method and the apparatus for selectively mixing sand or other solid polishing materials (such as glass beads) with a stream of pressurized fluids such as air, and then propelling them through an orifice wherein the solid material is basically under gravity feed actuation and the amount of sand that is allowed to mix with the air is controlled by a combination of a mechanical valve and the reaction of the solid material under the force of gravity to air turbulence within the pressurized system.

O I v United States Patent 1191 1111 3,793,778 Price Feb. 26,1974

[54] SAND BLAST APPARATUS 861,138 7/1907 Newell 51/3 [76] nvento RichardPrice 2116 w. t psc 3,032,929 5/l962 Glesener 5l/l2 X Ave., Baltimore,Md. 21230 I Primary Examiner-Donald G. Kelly [22 Filed: Feb. 25, 1970[2i] Appl. No.: 14,167 7 ABSTRACT I A method and the apparatus forselectively mixing [52] US. Cl. 51/12 sand other Solid polishingmaterials (such as glass [51] Int. Cl. B24c 5/02, B240 7/00 beads) witha Stream of pressurized fluids such as i [58] held of Search 51/8 321and then propelling them through an orifice wherein i the solid materialis basically under gravity feed actua- [56] References C'ted tion andthe amount of sand that is allowed to mix UN T STATES PATENTS with theair is controlled by a combination of a me- 968,350 8/1910 Harrison;51/11 1.1x h ni al al and the reaction of the solid material 885,0694/1908 Mullikin under the force of gravity to air turbulence within the2,305,976 12/1942 McKnight..... pressurized system.

346,650 8/1886 Freeman 699,405 5/1902 Newhouse 51/12 3 Claims, 3 DrawingFigures i SAND BLAST APPARATUS BACKGROUND OF INVENTION This equipment isone of a series of similar pieces of equipment designed for selectivelyapplying abrasives or other solid material in a fluid such as air orliquid wherein the abrasive is variously admitted to the fluid airstream by venturi action, gravity action, pressure action, mechanicalvalve action, and similar actions whereby there is a regulating of themixture between the air and the solid particles.

Prior Art The Prior Art consists largely of a venturi or pressure or agravity method of mixing the sand with a stream of air. Examples of thisare shown in U.S. Pat. Nos. 2,766,558 by Black; 3,032,929 by Glesener;1,706,222 by Fatscher; 2,938,305 by Bipes; 2,372,957 by Keefer; and671,303by Warren. The Warren apparatus seems to be basically amechanically controlled gravity flow device with a method of pressureequalization. The Keefer device has a curved throat which joins with anenlarged or venturi type chamber area indicating that it appears tooperate by a vacuum or pressure differential principle and Bipes appearsto have a pressure assist to that general principle and Fatscher againuses the venturi or suction-pressure differential principle whileGlesener and Black work on a mixing chamber where air, sand are mixedand further adjusted by suction for the feed of the sand/air mixture.Most of these devices stated above use quite a bit of the working powerof the air to move the sand from the position of storage into theposition where it is mixed with air in the high velocity chamber priorto expelling it through an orifice. Of course, this is true except forthe simple gravity-feed devices. The gravity-feed devices require adelicate balance between the air pressure and the gravity pressureswhich must be adjusted by the various valves. The gravity pressure thendiffers as the amount of sand is used. In the subject invention, airturbulence is used to provide a back pressure to support the sand and toresist the action of gravity and as such, this tends to equalize theamount of sand mixed with air at a particular time and does notunnecessarily waste energyof the air in moving the sand. Also, thisdevice has three distinct modes of operation which give an advantage offlexibility of operation; adjustable sand orifice, adjustable airorifice and no adjustable orifices.

SUMMARY OF THE INVENTION This invention consists of a device which, whenattached to a supply of air pressure, and the air pressure is adjustedfor optimum results, allows a gravity operation of sand or otherabrasive against a sand valve regulator and against a turbulence in theair pressure tube and by the combination of the action of the valve, theair pressure, the turbulence created by the flow of air, allow for apropelling 'of the abrasive material with a substantial savings involume and air pressure necessary to achieve the same amount ofpropelling. Thus, the device, for example, will allow sand blasting tooccur preferably with a simple air compressor such as one-thirdhorsepower 1$ h.p.) operating at 35 to40 lbs. pressure through a 5/32inch to 7/32 inch orifice.

orifice in order to achieve the same rate of sand abrasive action. (SeeEmpire Abrasive Equipment Corp., 3063 Miller Street, Philadelphia, Pa.19134, catalogue page 19.)

DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross-section,elevational view of the subject invention.

FIG. 2 is an alternative of FIG. 1 in an elevational drawing showing onemodification; that is, one of no air control valve and showing it in theoperative and alternative inoperative position.

FIG. 3 is an elevational view of a third modification of the subjectdevice showing a simplified version of FIG. 1 wherein there are novalves for either the sand or the air, and on-off operation is achievedby placing the device in the alternative position.

A listing of the parts involved in this device is as follows: 10 is thelow-pressure abrasive gun; 12 is the abrasive container; 14 is the sandor other abrasive or polishing material such as glass beads; 16 is thethroat or container adapter for attaching the sand cup; 18 is Y theabrasive-valve handle; 20 is the abrasive conduit to Under all of theexisting conventional forms of sand blasting equipment, it would benecessary, in order to achieve the same delivery of abrasive sand, to goto as much as 3 h.p. and to lbs. air pressure with 3 to 5 cu. ft. perminute and approximately the same size allow the sand to enter the valvechamber area;'22 is the valve orifice. The air supply valve handle is24; the air supply valve orifice is 26; the threads or other devices(shown but not claimed) for attaching the inven-' 'tion to the supply ofair is 28; air supply is 30. The nozzle is 32; with the nozzle orifice34. Within the tube, the air transit tube, there are three parts to thisair chamber marked as a, b, and c.

In the preferred embodiment of the subject invention, you have a supplyof sand 14, or otherabrasive or polishing material contained in airtightchamber 12, which is attached to an adapting conduit 16 and this sand bygravity, is forced down to the conduit area of 20. The T-shaped airchambers a, b, and c are connected so that air pressure from a source isusually about 35 to 40 lbs. pressure per sq. in. at 2 to 3 cu. ft. perminute, is regulated through the valve handle 24 and valve orifice 26into chamber a. There the air will flow, and assuming sand valve 18 tohave its orifice 22 closed, and then proceed straight down a to c and onout through orifice 34. As a matter of interest, this procedure of theair flowing down from a through c takes place in a slightly spiralmanner, as a rule. It is believed that this is due to the Coriolisforce, having to do with earths gravity; however, by furtherobservation, it is shown that the air also proceeds not only from a to cbut a portion of it goes up one side wall of the conduit area B andcomes down the other sidewall, making, in effect, an incursive letter eshape. Thus the air sets up a turbulence just below the valve orifice 22where a portion of this air passing from 30 to 34 must turn around as itgoes up the little side aisle b. When valve orifice 22 is open to allowsome sand to drift down by gravity, the first thing that must beovercome is a little bit of backpressure due to the fact that the airflowing up one side of tube b and down the other, and turning aroundright at the entrance of the orifice 22. This action tends to clean outthe orifice and blow the sand back against gravity. With 40 lbs. ofpressure, this is merely a slight backpressure and not sufficient toprevent the gravity flow of one to 4 or 5 inches of sand pressure.However, with an air pressure of 60 or lbs., and all other conditionsbeing the same, the turbulence just below the valve would be sufficientto suspend the one to inches of sand and not let it come down, eventhrough a fully opened orifice. It is this action and reaction of theair of turning around just below this valve that it is believed ispartly responsible for the good performance and ease of cleaning thisdevice because now the device can operate at almost 0 work conditionsinsofar as the amount of air that must be used to move the sand into theproper propelling path of channel c and on through orifice 34. Ofcourse, at this point it is clearly seen that by restricting orifice 34,the volume of air or air and sand or other particulate matter can bematched to the volume output of your pump and thus in one modification(FIG. 2) all that is needed is a valve 18 for the sand tube to adjustthe ratio of sand to air, that is desired. For an inoperative position,merely move the cup to position 36 (FIG. 2) cutting off the supply ofsand without changing position of the abrasiveflow rate valve 18. Theair going through the orifice 34 being matched to the pump capacity(equal to or less than) and being the only other operation necessary toturn the air supply pump (not shown) on and off at the beginning orending of a complete work period. A still further simplification isshown in FIG. 3 whereby adjusting the size of the opening in throat 20in a fixed amount and setting the orifice to match the pump capacity, afixed sand-to-air ratio mixture can be operated by simple attachment toan air supply and the sand blasting operation is merely activated orstopped by placing the cup in the upper or lower position.

What I claim is:

1. In adevice for propelling particulate abrasive material by means offluid pressure flow the improvement comprising;

a. a first fluid pressure flow path conduit of substantially uniformcross section with an inlet opening at one end and a substantiallysmaller outlet opening at the opposite end, and a third opening spacedfrom said two ends at the side of said conduit, b. a second conduit ofshorter length than said first conduit but of same cross sectional ofdiameter located perpendicular to said first conduit and having one endconnected to said third opening in said first conduit, and having theremaining end detachably connected to an enlarged closed chamber, forthe storage of particulate matter, whereby said fluid flow isturbulently directed substantially in a cursive e path having the top ofthe e" located substantially at the junction of the chamber and saidsecond conduit, and whereby said fluid flow path means can be orientedto selectively receive by gravity introduction the particulate matterand expelled at said first conduit exit end. 2. In a device forpropelling particulate material of the character designated in claim 1wherein said second conduit has a valve athwart the fluid path forselectively connecting said flow path with said enlarged chamber. 4

3. In a device for propelling particulate material of the characterdesignated in claim 1 wherein said outlet opening is one-thirdto'one-twentieth the diameter of said first conduit.

1. In adevice for propelling particulate abrasive material by means offluid pressure flow the improvement comprising; a. a first fluidpressure flow path conduit of substantially uniform cross section withan inlet opening at one end and a substantially smaller outlet openingat the opposite end, and a third opening spaced from said two ends atthe side of said conduit, b. a second conduit of shorter length thansaid first conduit but of same cross sectional of diameter locatedperpendicular to said first conduit and having one end connected to saidthird opening in said first conduit, and having the remaining enddetachably connected to an enlarged closed chamber, for the storage ofparticulate matter, whereby said fluid flow is turbulently directedsubstantially in a cursive ''''e'''' path having the top of the''''e'''' located substantially at the junction of the chamber and saidsecond conduit, and whereby said fluid flow path means can be orientedto selectively receive by gravity introduction the particulate matterand expelled at said first conduit exit end.
 2. In a device forpropelling particulate material of the character designated in claim 1wherein said second conduit has a valve athwart the fluid path forselectively connecting said flow path with said enlarged chamber.
 3. Ina device for propelling particulate material of the character designatedin claim 1 wherein said outlet opening is one-third to one-twentieth thediameter of said first conduit.